Marker manager (#3497)

* Adds a marker manager

core/marker_manager.js

@@ -0,0 +1,182 @@
+/**
+ * @license
+ * Copyright 2019 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @fileoverview Object in charge of managing markers and the cursor.
+ * @author aschmiedt@google.com (Abby Schmiedt)
+ */
+'use strict';
+
+goog.provide('Blockly.MarkerManager');
+
+goog.require('Blockly.Cursor');
+goog.require('Blockly.Marker');
+
+
+/**
+ * Class to manage the multiple markers and the cursor on a workspace.
+ * @param {!Blockly.WorkspaceSvg} workspace The workspace for the marker manager.
+ * @constructor
+ * @package
+ */
+Blockly.MarkerManager = function(workspace){
+  /**
+   * The cursor.
+   * @type {Blockly.Cursor}
+   * @private
+   */
+  this.cursor_ = null;
+
+  /**
+   * The cursor's svg element.
+   * @type {SVGElement}
+   * @private
+   */
+  this.cursorSvg_ = null;
+
+  /**
+   * The map of markers for the workspace.
+   * @type {!Object<string, !Blockly.Marker>}
+   * @private
+   */
+  this.markers_ = {};
+
+  /**
+   * The workspace this marker manager is associated with.
+   * @type {!Blockly.WorkspaceSvg}
+   * @private
+   */
+  this.workspace_ = workspace;
+};
+
+/**
+ * Register the marker by adding it to the map of markers.
+ * @param {string} id A unique identifier for the marker.
+ * @param {!Blockly.Marker} marker The marker to register.
+ */
+Blockly.MarkerManager.prototype.registerMarker = function(id, marker) {
+  if (this.markers_[id]) {
+    this.unregisterMarker(id);
+  }
+  marker.setDrawer(this.workspace_.getRenderer()
+      .makeMarkerDrawer(this.workspace_, marker));
+  this.setMarkerSvg(marker.getDrawer().createDom());
+  this.markers_[id] = marker;
+};
+
+/**
+ * Unregister the marker by removing it from the map of markers.
+ * @param {string} id The id of the marker to unregister.
+ */
+Blockly.MarkerManager.prototype.unregisterMarker = function(id) {
+  var marker = this.markers_[id];
+  if (marker) {
+    marker.dispose();
+    delete this.markers_[id];
+  } else {
+    throw Error('Marker with id ' + id + ' does not exist. Can only unregister' +
+        'markers that exist.');
+  }
+};
+
+/**
+ * Get the cursor for the workspace.
+ * @return {Blockly.Cursor} The cursor for this workspace.
+ */
+Blockly.MarkerManager.prototype.getCursor = function() {
+  return this.cursor_;
+};
+
+/**
+ * Get a single marker that corresponds to the given id.
+ * @param {string} id A unique identifier for the marker.
+ * @return {Blockly.Marker} The marker that corresponds to the given id, or null
+ *     if none exists.
+ */
+Blockly.MarkerManager.prototype.getMarker = function(id) {
+  return this.markers_[id];
+};
+
+/**
+ * Sets the cursor and initializes the drawer for use with keyboard navigation.
+ * @param {Blockly.Cursor} cursor The cursor used to move around this workspace.
+ */
+Blockly.MarkerManager.prototype.setCursor = function(cursor) {
+  if (this.cursor_ && this.cursor_.getDrawer()) {
+    this.cursor_.getDrawer().dispose();
+  }
+  this.cursor_ = cursor;
+  if (this.cursor_) {
+    var drawer = this.workspace_.getRenderer()
+        .makeMarkerDrawer(this.workspace_, this.cursor_);
+    this.cursor_.setDrawer(drawer);
+    this.setCursorSvg(this.cursor_.getDrawer().createDom());
+  }
+};
+
+/**
+ * Add the cursor svg to this workspace svg group.
+ * @param {SVGElement} cursorSvg The svg root of the cursor to be added to the
+ *     workspace svg group.
+ * @package
+ */
+Blockly.MarkerManager.prototype.setCursorSvg = function(cursorSvg) {
+  if (!cursorSvg) {
+    this.cursorSvg_ = null;
+    return;
+  }
+
+  this.workspace_.getBlockCanvas().appendChild(cursorSvg);
+  this.cursorSvg_ = cursorSvg;
+};
+
+/**
+ * Add the marker svg to this workspaces svg group.
+ * @param {SVGElement} markerSvg The svg root of the marker to be added to the
+ *     workspace svg group.
+ * @package
+ */
+Blockly.MarkerManager.prototype.setMarkerSvg = function(markerSvg) {
+  if (!markerSvg) {
+    this.markerSvg_ = null;
+    return;
+  }
+
+  if (this.workspace_.getBlockCanvas()) {
+    if (this.cursorSvg_) {
+      this.workspace_.getBlockCanvas().insertBefore(markerSvg, this.cursorSvg_);
+    } else {
+      this.workspace_.getBlockCanvas().appendChild(markerSvg);
+    }
+  }
+};
+
+/**
+ * Dispose of the marker manager.
+ * Go through and delete all markers associated with this marker manager.
+ * @suppress {checkTypes}
+ * @package
+ */
+Blockly.MarkerManager.prototype.dispose = function() {
+  var markerIds = Object.keys(this.markers_);
+  for (var i = 0, markerId; (markerId = markerIds[i]); i++) {
+    this.unregisterMarker(markerId);
+  }
+  this.markers_ = null;
+  this.cursor_.dispose();
+  this.cursor_ = null;
+};